The invention concerns a method to control a unit of a technical apparatus, whereby the apparatus can be operated in a plurality of operating circumstances in which the unit is controlled with a control command belonging to the respective operating circumstance.
The control of a unit of a technical apparatus typically ensues via a control program that is executed with the aid of a control unit. If the technical apparatus can be operated in different operating circumstances, this can have an influence on the type and manner of the control of the unit, for example, on its operating mode. If the control of the unit can be described with a few options, it is typical to permanently incorporate these into the control program. This has the disadvantage that the use of the unit via the options predetermined by the control program is severely limited. If the unit is exchanged or changed with regard to its capability, the control program must take into account new or modified properties of the unit or the operating circumstance, since this can otherwise lead to complications. For the most part, the control program must be elaborately adapted.
A further disadvantage is that the control program must from the outset take into account the entire complexity in the control of the units. The more complex the operating circumstances and the units to be controlled, the more impractical this procedure is. Furthermore, it is difficult to anticipate which future developments must be taken into account in the control program.
Such a problem results, for example, in the operation of a magnetic resonance (MR) apparatus with a plurality of attachable coil units. Depending on the type of the MR measurement (operating circumstance), specific coil units are used as transmission and/or reception antennas. For this, the coil units are connected with a control unit of the MR apparatus via a plug and a bushing that, for example, is integrated into a patient bed. The connection ensues via a plurality of channels, for example, a plurality of reception and transmission channels, a plurality of channels for the identification of the coil unit, and a plurality of channels for control of the coil unit. The coil units can be controlled in various operating modes in which, for example, one of the control channels is engaged with a voltage or with a current flow. In a third possibility, the operating mode of the coil unit is dependent on the type of the engagement of the control channel. One of the control channels can, for example, be used to tune or detune the antenna to a frequency upon transmitting or receiving radio-frequency signals.
In coil units that are suitable for transmission or reception of RF signals of a single nucleus, for example hydrogen, an operating circumstance can be described by a few options. This description is easily adopted into a control program of the MR apparatus. If a coil unit is connected with the MR apparatus, its coil data is read in that the various operating modes of the control channels are described. Depending on the operating circumstance, the corresponding control of the coil unit ensues.
This type of the control of the control channels of coil units has a disadvantage that, for example, given the use of multicore coils, the consideration of all various operating circumstances in the control program of the MR apparatus would lead to very complex program structures. Additionally, a coil unit that requires a new property of one of the operating circumstances to adjust its operating mode, this property not yet haven been taken into account in the control software, can only be used after an expansion of the control program.
From German patent document DE 197 07 241 C2, a safety switch apparatus with a notification device is known that comprises two switch states. After a detected connection of a notification device, it is checked whether the “correct” switch state is present. If this is the case, the safety switch apparatus is released.
From German patent document DE 44 30 646 A1, an RF probe for a magnetic resonance apparatus is known which comprises two coils with variable separation. An optimized compensation circuit is used dependent on the separation.